<template>
  <div>
    <router-link tag="div" to="/" class="header-abs" v-show="showAbs">
      <div class="iconfont detail-header-back">&#xe624;</div>
    </router-link>
    <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
      <router-link tag="div" to="/">
        <div class="iconfont detail-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>

</template>

<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {opacity: 0}
    }
  },
  methods: {
    handleScroll () {
      let top = document.documentElement.scrollTop
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = {opacity: opacity}
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  activated () {
    window.addEventListener('scroll', this.handleScroll)
  },
  deactivated () {
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>

<style scoped lang="stylus">
  @import "~styles/variables.styl"
.detail-header-back
  width:.8rem;
  height:.8rem
  border-radius:.4rem
  background:rgba(0,0,0,0.8)
  text-align:center;
  line-height:.8rem;
  color:#fff
  position:fixed;
  top:.2rem;
  left:.2rem;
  z-index:2
.header-fixed
  height:$height
  position:fixed;
  top:0;
  background:$bgColor
  width:100%
  line-height:$height
  color:#fff
  text-align:center
  .detail-fixed-back
    position:absolute;
    top:0;
    left:.2rem
</style>
